MARIEMONT, Ohio — Crisp is unlike most dogs; when he fetches something, it's not a game. It's his job.

The Labrador-golden retriever mix is an assistance companion to 8-year-old Mason Murphy, a Mariemont Elementary student whose cerebral palsy prevents him from using his legs and contributes to other difficulties.

Every night before Mason goes to bed, Crisp helps pull off his clothes and socks. The dog opens and closes doors and pushes elevator buttons and participates with Mason's physical therapy.

"Anywhere Mason goes, the dog goes," says Page Murphy of Mariemont, Mason's mother. "Mason had surgery last week; the dog was in the hospital with him all week. They're inseparable. They're best buddies."

"Crisp, get!" Mason said recently after he dropped a doll's hairbrush on the floor near his electric wheelchair.

Crisp's tail stops wagging and points straight out as the dog tries to pick up the brush in his mouth. It takes a few tries, but he soon gets it firmly in his jaws.

"Crisp, give!" Mason says and the dog puts his paws on the wheelchair's shelf and offers the brush to Mason, who takes it from him.

"Now we have to go back to the castle," Mason says and zips over to another part of the playroom with Crisp.

"Mason loves dogs," Murphy added. "But every dog he'd see would run away from him and he would get frustrated. Crisp never leaves his side."

Murphy said the dog has helped her soft-spoken son become more outgoing.

"When Mason is out with the dog, a lot of the attention is taken off of him and his wheelchair and people focus on the dog, which is nice," she said. "It helps him make friends, and the companionship is awesome."

Mason says he feels less shy.

"He's my friend. I love Crisp," Mason said.

Murphy found out about assistive dogs at a cerebral palsy conference more than two years ago. She put their names on a waiting list at Canine Companions for Independence, which is based in Santa Rosa, Calif., but has a regional training center in Delaware, Ohio.

Murphy and Mason waited two years for a dog that suited their needs.

Canine Companions breeds the dogs — Labradors, retrievers or mixes of the two — in California, where volunteers raise them over the next year or so. The dogs are professionally trained.

It can cost Canine Companions up to $45,000 to raise and train the dogs, but the nonprofit does not charge the families who receive the dogs.

Including Crisp, there are at least nine Canine Companion assistance dogs in the Cincinnati region helping people with physical disabilities, not counting visually impaired individuals, who get guide dogs from other agencies.

Canine Companions also provides hearing dogs and dogs that help in hospitals, schools and rehabilitation facilities.

The Murphys received Crisp in August and underwent their own training for two weeks, learning how to give Crisp commands. The dog knows more than 40 commands.